The present invention relates to body implantable treatment devices, and more particularly to apparatus for securing such devices at predetermined locations within the body.
A wide variety of patient treatment and diagnostic procedures involve the use of devices inserted into the body of the patient, with some of these devices being either temporarily or permanently implanted. Among the permanently implanted devices are prostheses or grafts for transluminal implantation, for example as disclosed in U.S. Pat. No. 4,655,771 (Wallsten). The prosthesis described in Wallsten is a flexible tubular braided structure formed of helically wound thread elements. Gripping members at opposite ends of the prosthesis initially secure it to a catheter, with the proximal gripping member being movable distally to give the tube the shape of a balloon. In deployment, the gripping members and catheter are removed, leaving the tube to assume a cylindrical shape.
Another device, disclosed in U.S. Pat. No. 4,793,348 (Palmaz), is a balloon expandable vena cava filter. The filter has an open weave structure, and can be provided with hooks at terminal ends of the strands forming the weave for securing the filter to body tissue. The filter is said to prevent lower extremity venous clots from migrating into the pulmonary circulatory system.
U.S. Pat. No. 4,699,611 (Bowden) is directed to a biliary stent which is tubular and provided with axially running slits which form parallel strips. The strips become flowered to form a Mallecot tip when relaxed, but collapse when the stent is maintained in tension. Other permanently implanted devices include electrically conducted intravascular leads for cardiac pacing or defibrillation devices, and catheters for delivering drugs or sensing temperatures, flow rates or other conditions within the body. Catheters frequently are used temporarily, with no intention of even temporary implantation, for example in percutaneous transluminal catheter angioplasty (PTCA) procedures.
Pacing leads typically are sufficiently flexible and small in diameter for intravenous introduction to the cardiac cavity, whereupon an electrode at the distal end of the lead is implanted into the endocardium to secure the lead. For this purpose, helical coils, barbs and other anchoring elements are provided, usually as part of the electrode. The anchoring element must be sufficiently sharp to penetrate the endocardium and secure the electrode against becoming detached, for example due to contractions of the myocardium. A problem with such anchoring elements is that they can become entangled in the vein, heart valve or other tissue encountered during intravenous insertion. Flexible outwardly extended tines, usually constructed of plastic, afford a safer intravenous insertion of the lead, yet do not provide the positive anchoring of helical coils or the like.
An example of a temporarily implanted treatment device is the Foley catheter, designed to overcome an obstruction in the urinary tract, or a constriction due to collapse of the sphincter during and after surgery. Typically, a catheter is fixed in the urinary tract near the opening into the bladder by means of a dilated balloon. One disadvantage of this approach, however, is due to the surface area where the fixation balloon and urinary tract are contiguous. This area retains moisture which promotes the growth of harmful bacteria and can lead to infection, spreading throughout the urinary tract.
Thus, there remains a need for a positive fixation device which is reliable, convenient to deploy and minimizes the chance of infection.
Therefore, it is an object of the present invention to provide a fixation means particularly well suited for securing implantable devices within body cavities.
Another object is to provide a fixation means adaptable for either temporary or permanent placement within the body.
Yet another object is to provide a fixation means for catheters and other diagnostic and treatment devices to provide a positive initial securement and improved long-term fixation by promoting fibrosis, while reducing the probability of infecting tissue in the region of fixation.